It is not by any means rare for a mountaineer to take the wrong route and go missing, and in recent years has happened many times. Also, accidents due to getting lost are not limited to mountaineering, and occur in various outdoor locations such as at sea and in the forest. Technology has been proposed so as to solve these kinds of problems with mobile phones having a GPS function (refer to Patent Document 1). In such technology, first, positional information and map data for a destination are imported from a car navigation system into a mobile phone. Then, navigation can be continuously performed with information from the mobile phone for a person who intends to move on foot from the position where he/she has alighted from the vehicle to the destination.